Known flame-retardant thermoplastic resin compositions or flame retardants therefor include, for example, a flame-retardant resin composition containing a halogenated epoxy resin as a flame retardant as disclosed in JP-A-53-74557, JP-A54-91557, JP-B-60-264313, and JP-A-62-15256 (the term"JP-A" as used herein means an "unexamined published Japanese patent application", and the term "JP-B" as used herein means an "examined Japanese patent publication"); a flame-retardant resin composition further containing a flame-retardant assistant, e.g., antimony trioxide, as disclosed in JP-A-62-15256; a flame retardant comprising an epoxy resin whose epoxy groups are blocked by a halogenated phenol compound, e.g., tribromophenol, as disclosed in JP-A-62-4737; and a flame retardant system comprising a combination of a brominated bisphenol compound, an epoxy compound, and a metallic soap, e.g., calcium stearate.
However, since the conventionally proposed flame retardants have high stickiness to metallic parts of a molding machine or a mold, compounding of such flame retardants causes reduction in releasability of a molded article from a mold. Besides, the flame retardant sticking and remaining on the metallic parts undergoes thermal decomposition to cause discoloration or scorching.
It is generally known to improve mold releasability by addition of long chain aliphatic carboxylic acids, e.g., stearic acid, as a release agent. The release agent is usually incorporated by dry blending with resins and flame retardants, followed by melt kneading in an extruder, etc.
However, in using a halogenated epoxy resin as a flame retardant, it has been difficult to obtain a flame-retardant resin composition exhibiting easy release even with the aid of the known release agent. Stick in mold due to a flame retardant is particularly conspicuous with resins requiring high molding temperatures such as polyester resins.